Whether Mariota’s “stinger’’ issue subsides to the point he’s able to start or the Titans once again must turn to Gabbert undoubtedly will drive pre-game conversation.

Mariota has been the face of the franchise since being taken with the second overall pick in the 2015 draft. Gabbert was selected 10th overall by Jacksonville in 2011, flamed out with the Jaguars – 5-22 as a starter in three seasons – and bounced around the league before signing with Tennessee in March.

The Colts faced both in their 38-10 blowout in mid-November. Mariota started but was knocked out of the game in the second quarter. Gabbert finished.

“Yeah, they are both good quarterbacks and they are kind of similar,’’ Frank Reich said. “They are both athletic. They’ve got a lot of confidence in both of them.

“I think they both fit their system very well.’’

But again: Derrick Henry.

“We all know they want to run the football,’’ Reich said, adding Henry “is an elite back.’’

That’s certainly been the case in December. Consider Henry’s last three games: 71 carries, 492 yards (6.9 per attempt), seven touchdowns. In his first 12 games, he rushed for 474 yards and averaged 3.7 yards per attempt.

The flashpoint occurred in week 14 against Jacksonville when Henry set a franchise record with 238 yards and four touchdowns.

“I have known him for a while growing up in Florida,’’ linebacker Anthony Walker said. “So I have seen him. He’s as good as advertised. He’s big, he’s explosive and when he gets outside he’s a problem in the open field.’’

Henry is one of the NFL’s bigger backs: 6-3, 247. To drive home the point, consider his listed weight is more than any of the Colts’ linebackers.

The primary objective in limiting Henry’s effectiveness? Swarm to the football.

“It’s going to take everybody,’’ coordinator Matt Eberflus said.

Added Reich: “Population to the ball. Seven, eight guys to the ball. You’ve got to cap him off because he can come squirting out of there. He is just hard to bring down.’’

The Colts’ defense has grown as the season has unfolded, but effective work against the run has been a constant. It ranks eighth in yards per game allowed (102.2), sixth in yards per attempt (3.8) and has yet to allow a 100-yard rusher.

Moreover, the defense has faced six of the NFL’s top-11 rushers – Ezekiel Elliott, Saquon Barkley, Joe Mixon, Adrian Peterson, Henry and Lamar Miller – and more than held its own. That group has averaged 86.1 yards per game and 4.8 yards per rush against the league. In seven games against the Colts, the averages dip to 53.2 per game and 3.6 per attempt.

Kelly out, Ebron close

Center Ryan Kelly and rookie receiver Reece Fountain have been ruled out of Sunday’s game.

Tight end Eric Ebron went through a second straight practice Friday but still needed clearance from an independent neurologist in his progress through the NFL’s concussion protocol.

Kelly revealed he suffered damage to a nerve in his neck in the second quarter of last Sunday’s win over the New York Giants. It caused him to lose strength in one of his arms.

“They were worried about the nerve that runs in there,’’ Kelly said. “You can just hurt it a lot worse, which is why I didn’t go back in the game. A lot of times if you get one, it’ll go away. But the strength wasn’t coming back at halftime.’’

A magnetic resonance imaging test revealed no fractured vertebrae, but “there was enough there that they were like, ‘We can’t send you back out there,’’’ Kelly said.

“We’re just being cautious with the neck, especially with Slauson having that super neck injury.’’

Matt Slauson started the first five games at right guard before suffering two fractured vertebrae in his back and being placed on the injured reserve list.

Kelly isn’t certain how long it will take for him to recover, but the team has not placed him on IR and hopes he’s available if it makes the playoffs.

“You can’t push it too hard because it’s a neck and it’s a sensitive area,’’ he said. “At the end of the day you don’t want to railroad your career and go out there and really (mess) your neck up.’’